BearSSL/T0/CodeElement.cs

101 lines
2.5 KiB
C#

/*
* Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
using System;
abstract class CodeElement {
internal int Address { get; set; }
internal int LastLength { get; set; }
// internal abstract int Length { get; }
internal CodeElement()
{
Address = -1;
}
internal virtual void SetJumpTarget(CodeElement target)
{
throw new Exception("Code element accepts no target");
}
internal abstract int GetLength(bool oneByteCode);
internal abstract int Encode(BlobWriter bw, bool oneByteCode);
internal static int EncodeOneByte(uint val, BlobWriter bw)
{
if (val > 255) {
throw new Exception(string.Format(
"Cannot encode '{0}' over one byte", val));
}
bw.Append((byte)val);
return 1;
}
internal static int Encode7EUnsigned(uint val, BlobWriter bw)
{
int len = 1;
for (uint w = val; w >= 0x80; w >>= 7) {
len ++;
}
if (bw != null) {
for (int k = (len - 1) * 7; k >= 0; k -= 7) {
int x = (int)(val >> k) & 0x7F;
if (k > 0) {
x |= 0x80;
}
bw.Append((byte)x);
}
}
return len;
}
internal static int Encode7ESigned(int val, BlobWriter bw)
{
int len = 1;
if (val < 0) {
for (int w = val; w < -0x40; w >>= 7) {
len ++;
}
} else {
for (int w = val; w >= 0x40; w >>= 7) {
len ++;
}
}
if (bw != null) {
for (int k = (len - 1) * 7; k >= 0; k -= 7) {
int x = (int)(val >> k) & 0x7F;
if (k > 0) {
x |= 0x80;
}
bw.Append((byte)x);
}
}
return len;
}
}